本文實(shí)例實(shí)現(xiàn)一個(gè)倒計(jì)時(shí)功能. 倒計(jì)時(shí)功能, 用在項(xiàng)目的發(fā)布時(shí)間, 或者某個(gè)活動(dòng)做倒計(jì)時(shí)等等的突出時(shí)間功能的方面.
界面代碼結(jié)構(gòu),先要完成好. 這個(gè)界面我就不做那么美觀了,湊合就行(O(∩_∩)O哈哈~).

代碼名稱

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>倒計(jì)時(shí)實(shí)現(xiàn)</title>
  <style>
    ul, li {
      margin: 0;
      padding: 0;
      list-style: none;
    }
    #countdown {
      font-size: 50px;;
      width: 350px;
      margin: 0 auto;
      background-image: none;
      color: #fff;
      padding: 100px;
      font-weight: bolder;
    }
    #countdown ul {
      display: flex;
      align-items: flex-start;
      justify-content: center;
    }
    #countdown ul li{
      display: inline-block;
      margin-left: 10px;
    }
    #countdown ul li:last-child {
      margin-right: 10px;
    }

    #countdown ul li strong {
      text-shadow: 5px 5px 5px #000;
    }
    #countdown ul li strong, #countdown ul li span {
      display: block;
      text-align: center;
    }
    #sec {
      color: #ff0000;
      text-shadow: 5px 5px 2px #ff0000;
    }
  </style>
</head>
<body>
  <div id="countdown">
    <ul>
      <li>
        <strong id="day">00</strong>
        <span>天</span>
      </li>
      <li>:</li>
      <li>
        <strong id="hour">00</strong>
        <span>時(shí)</span>
      </li>
      <li>:</li>
      <li>
        <strong id="min">00</strong>
        <span>分</span>
      </li>
      <li>:</li>
      <li>
        <strong id="sec">00</strong>
        <span>秒</span>
      </li>
    </ul>
  </div>
</body>
</html>

下面做Javascript的講解了.

首先設(shè)定一個(gè)結(jié)束時(shí)間,時(shí)間通過new Date()來進(jìn)行創(chuàng)建. 這樣才能夠計(jì)算倒計(jì)時(shí)的時(shí)間.

//結(jié)束時(shí)間
var t_endtime = new Date("2016-05-22 00:00:00");

然后就是換算規(guī)則,規(guī)則的換算是常理了.

// 時(shí)間換算規(guī)則
var t_day = 60 * 60 * 24;
var t_hour = 60 * 60;
var t_min = 60;

再次就是通過setInterval來計(jì)算當(dāng)前時(shí)間的對比, 因?yàn)闀r(shí)間在一秒一秒的過去, 當(dāng)前時(shí)間的獲取就在setInterval中進(jìn)行計(jì)算. 當(dāng)然還得將計(jì)算出的結(jié)果顯示到界面上.

var ele_day = document.getElementById("day");
var ele_hour = document.getElementById("hour");
var ele_min = document.getElementById("min");
var ele_sec = document.getElementById("sec");

setInterval(function () {
  //獲取當(dāng)前時(shí)間
  var t_currenttime = new Date();
  //結(jié)束時(shí)間 - 當(dāng)前時(shí)間 = 剩余時(shí)間
  var t_result = t_endtime.getTime() - t_currenttime.getTime();

  //剩余時(shí)間換算
  var t_time = Math.floor( t_result / 1000 );
  var t_result_day = Math.floor( t_time / t_day );
  var t_result_hour = Math.floor( t_time % t_day / t_hour);
  var t_result_min = Math.floor(t_time % t_day % t_hour/ t_min);
  var t_result_sec = Math.floor( t_time % t_day % t_hour % t_min);

  // 將時(shí)間小于10的,在值前面加入0;
  if ( t_result_day < 10) {
    t_result_day = "0" + t_result_day;
  }

  if ( t_result_hour < 10) {
    t_result_hour = "0" + t_result_hour;
  }

  if ( t_result_min < 10) {
    t_result_min = "0" + t_result_min;
  }

  if ( t_result_sec < 10) {
    t_result_sec = "0" + t_result_sec;
  }

  //顯示到頁面上
  ele_day.textContent = t_result_day;
  ele_hour.textContent = t_result_hour;
  ele_min.textContent = t_result_min;
  ele_sec.textContent = t_result_sec;

}, 1000);

很簡單, 一個(gè)倒計(jì)時(shí)功能就完成了.